Determine the dot printing process according to the characteristics of the substrate

The practice of the offset printing process shows that in order to completely transfer the dots on the surface of the blanket to the surface of the paper, only the paper with a relatively smooth paper surface can better express the level and dot shape of each tone of the original. Rough paper paper to print dot products will inevitably produce defective quality defects, which will directly affect the subtle level of performance of printed products. Experiments show that the higher the number of network lines, the smaller the dot diameter. In this case, if there is a slight depression on the surface of the paper, the dot on the print is bound to appear incomplete. If the use of increased printing pressure or increase the layout of the ink supply to make up for the lack of contact between the layout and the paper surface, it will cause the spread of ink and cause dot gain. Therefore, good paper smoothness is an important condition for printing high quality outlets.

The finer products with the highest number of screens, the higher the paper's smoothness, which is a basic principle of the printing process. However, in practical work, considering the practicability and economy of the product, the paper often used is not determined by the printing unit unilaterally. Under the constraints of objective conditions, appropriate printing process measures should be taken in order to ensure the printing quality. This can be adjusted to certain printability by adjusting certain properties of the ink or changing process measures. For example, paper with poor print smoothness may be appropriately increased in printing pressure, and use ink with high fluidity and strong lubricity, so that it can overcome and compensate for defects in imprint quality caused by poor paper smoothness. On the other hand, if printing a paper with good smoothness, the printing pressure can be appropriately reduced, and inks with higher viscosity and stronger adhesion can be used. Of course, the above situation is not absolute and cannot be applied mechanically or blindly. Even if there are two papers with similar smoothness, due to their structural differences, there should be differences in the selection of inks. For example, for papers filled with fillers and compounds to fill fiber gaps, and super calendered papers, because of their tighter paper structure, inks with less fluidity and higher viscosity can be used for printing. Imprinting. For a part of the long fibers as the skeleton, with sufficient short fibers to fill the gaps between the long fibers, and after the calendered treatment to provide a smooth surface of the paper, it must be printed with an ink with a larger fluidity and a lower viscosity. Avoid powder falling and pulling defects in the printing process.

Because of the difference in the smoothness of the paper, printing screens can be used to adjust the printing pressure, ink fluidity, and tackiness, as well as the printing plate according to the characteristics of the printing machine, the nature of the printing product, and the quality of the paper. That is, the appropriate number of screens for screen printing is selected to achieve a better printing process effect to ensure the printing quality of the outlets. Under normal circumstances, the quality of the paper is relatively rough, the printing press rotates faster, and a screen of 80 lpi to 100 lpi can be used when making a plate. The printing effect is good. For example, printing with placards, ordinary offset papers, newspapers, etc., can use 80 lpi to 100 lpi screen plate making. Secondly, for the printing of new year pictures and calendars with better offset paper, it is appropriate to use 100 lpi to 133 lpi screen printing. The third situation is the use of coated paper, painting newspapers and other materials, printing pictorial, postcards, desk calendar, product advertising, books and magazines and other printed matter, you can choose 150lpi ~ 175lpi screen printing plate. The fourth case is the use of high-grade coated paper, glass card printing fine pictures, product advertising, books and magazines cover, illustrations and packaging and decoration prints and other high-end products, you can choose to use 175lpi ~ 200lpi screen plate, in order to achieve a better printing process The effect improves the printing quality of outlets.

To sum up, according to the characteristics of the paper and comprehensively printing conditions, it is beneficial to scientifically and reasonably formulate the technical measures for the printing outlets to ensure the printing quality and improve the print durability of the printing plate. Only by adopting reasonable printing technology measures can we fundamentally improve the technological level of printed materials and enhance the market competition and vitality of products.